Merge branch 'es/do-not-let-rebase-switch-to-protected-branch'

"git rebase BASE BRANCH" rebased/updated the tip of BRANCH and checked it out, even when the BRANCH is checked out in a different worktree. This has been corrected. * es/do-not-let-rebase-switch-to-protected-branch: rebase: refuse to switch to branch already checked out elsewhere t3400: make test clean up after itself